1. Field of the Invention
The present invention relates to an electronic apparatus having a security function for theft prevention.
2. Description of the Related Art
Examples of this kind of electronic apparatus are audio apparatuses, such as a compact disc reproduction apparatus, a radio receiver, a magnetic tape reproduction apparatus and a television set, mounted on vehicles, such as cars. This kind of electronic apparatus mounted on a vehicle is in danger of being removed from the vehicle and stolen. To prevent theft, a conventional electronic apparatus is configured such that when the electronic apparatus is reconnected to its power source, such as a battery, a predetermined identification code (abbreviated as ID) is required to be input. Only when the input identification code is the predetermined authorized code, the intrinsic operation of the electronic apparatus is carried out. When the authorized identification code is not input, the intrinsic operation of the electronic apparatus cannot be carried out.
Furthermore, to ensure this theft prevention, the number of times other wrong identification codes are input repeatedly while the authorized identification code is not input is counted by a counter. When the count value reaches a predetermined value or more, the electronic apparatus enters a dealer carry-in mode. In order to cancel the dealer carry-in mode so that the electronic apparatus can carry out its intrinsic operation, the electronic apparatus must be carried in to the dealer, where a master code must be input in the electronic apparatus. The master code has been determined commonly to every product of the electronic apparatus. For this reason, this master code is not disclosed to users, but strictly retained by the dealer. The dealer is herein a store or workshop for such electronic apparatuses, or for cars on which such electronic apparatuses are mounted.
The facts that the identification code is necessary to make this kind of electronic apparatus carry out its intrinsic operation, and that the master code is necessary in the dealer carry-in mode of the electronic apparatus should be known widely and generally by advertisement, whereby the electronic apparatus is not targeted for theft, and can be prevented from being stolen.
In the above-mentioned prior art, when the number of times unauthorized identification codes are input by the user reaches a predetermined value or more, the electronic apparatus enters the dealer carry-in mode, in spite of no theft. In the case of a configuration wherein the user inputs the identification code by using numeric keys, for example, the user may forget the identification code, whereby the apparatus enters the dealer carry-in mode. In the case of a configuration wherein a part of the content recorded on a compact disc to be read by the compact disc reproduction apparatus of the user is used as the identification code, when the compact disc of the user is damaged or lost, or when a wrong compact disc is played back a plurality of times, the apparatus enters the dealer carry-in mode. In these prior arts, the apparatus having entered the dealer carry-in mode as described above must be carried in the dealer.
In the prior arts, therefore, the electronic apparatus having entered the dealer carry-in mode must be carried in the dealer by the user. Furthermore, the dealer must cancel the dealer carry-in mode so that the electronic apparatus can perform its intrinsic operation. As a result, much effort and cost are required to cancel the dealer carry-in mode of the electronic apparatus in the case of the prior arts.